Use of artificial-substrate samplers to identify relations between periphytic diatom community composition and hydro-limnological conditions in shallow lakes of Old Crow Flats, Yukon Territory (Canada)

Concern over effects of climate warming on shallow northern lakes elicits need for agency-led, long-term, biomonitoring programs to implement protocols applicable across large, remote landscapes. Here, we analyze composition of periphytic diatom communities accrued on artificial-substrate samplers in 33 and 48 lakes spanning broad hydrological gradients of the lake-rich Old Crow Flats (Yukon, Canada) during ice-free seasons of 2008 and 2009, respectively, to explore the ability of this approach to discern ecological responses to differences in basin hydrology and water chemistry. Multivariate analyses demonstrate water chemistry and periphytic diatom community composition differ among three isotope-defined hydrological lake categories (snowmelt-dominated, rainfall-dominated, intermediate). Some snowmelt-dominated lakes support moderate percent abundances of Rossithidium pusilla, Sellaphora laevissima, Tabellaria flocculosa str. III and T. fenestrata, associated with relatively high concentrations of major nutrients and DOC. Rainfall-dominated lakes have higher pH and ion content, yet diatom composition overlapped extensively with intermediate and snowmelt-dominated lakes. Water chemistry and diatom community composition did not differ between study years, despite almost four-fold greater snowfall in 2009. Thus, periphytic diatom communities on artificial-substrate samplers capture ecological differences across hydro-limnological gradients of Old Crow Flats, but longer time-series of data are required to assess their ability to track temporal responses to hydro-climatic variation.